The ADOPT study is a prospective, nested case-controlled and open label clinical trial. About 40 centers across China participate in this study with a planned 800 Chinese cases enrollment. All patients will receive optimal medical treatment. Patients who have successful CRT-P/D implant will be assigned to CRT group. According to the baseline evaluation, matched cases will be selected from the enrolled OPT(optimal medical treatment) alone group (Group for Selection). After successful match, the cases in Group for Selection enters into follow-up and become control group. The unmatched cases in the Group for Selection will be removed. If patients agree, after re-evaluation of the baseline situation, she or he may enter into Group for Selection again. Since patients know she/he already have a device implant and the examiners are aware of the grouping of the patients after seeing the incision scar and post-implant electrocardiogram, this study is open-label designed, however the executive committee will be kept blind when making event-adjudication. Prospectively defined primary end points for the study include combined all-cause mortality and hospitalizations. A variety of secondary end points will further define the efficacy and mechanism(s) of action of cardiac resynchronization in heart failure. The last date of the study shall be the day after 24 months of follow-up of the last enrolled patient. All cases collection complete in 2010 and study result will be reported in 2012.